A service provider has hitherto constructed a service with use of a function of a telecommunications carrier and provided a service such as sending a message to a user by using an e-mail address of the user held by the telecommunications carrier as a user ID for using the service, for example.
Further, a growing number of users subscribe to a plurality of telecommunications carriers and have a plurality of e-mail addresses, such as using a telecommunications carrier with use of a fixed network at home and using a telecommunications carrier with use of a mobile network on the move.
In such circumstances, when a service provider delivers a message to a user who subscribes to a telecommunications carrier, the service provider has requested the telecommunications carrier to deliver a message, and the telecommunications carrier has delivered the message to a designated user.
Further, in the case where a user receives services from a plurality of service providers, if the respective services are managed using different user IDs, there is a problem that it is troublesome to perform user authentication for each service. In order to solve such a problem, single sign-on technology using ID federation information that coordinates user IDs in the respective services is used, for example (cf. the non-patent document 1).
As a technique related to such ID federation, the patent document 1, for example, discloses a technique that collects information about a user by linking user IDs registered on a plurality of sites and delivers the collected result.
Further, the patent document 2, for example, discloses a technique that collects information about users for various service providers, extracts a user conforming to a condition based on the collected information and delivers a message to the user.    [Patent Document 1]    Japanese Unexamined Patent Application Publication No. 2005-128672    [Patent Document 2]    Japanese Unexamined Patent Application Publication No. 2004-54312    [Non-Patent Document 1]    “Liberty ID-FF Architecture Overview”, [online], Liberty Alliance project, [Searched on Aug. 15, 2007], Internet    <http://www.projectliberty.org/liberty/content/download/318/2366/file/draft-liberty-idff-arch-overview-1.2-errata-v1.0pdf>